7-Acylamino-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylic acids

ABSTRACT

New semisynthetic cephalosporins characterized by having structures with a 3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl group at position 3. Exemplary is the antibacterially effective 7-D-mandelamido-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid disodium salt.

This invention relates to a new series of cephalosporin compounds havingantibacterial activity and to intermediates useful for preparing them.The structures of the new compounds are characterized by having at the3-position a sulfoalkyl substituted 1,2,4-triazol group

Exemplary of the compounds of this invention are those represented bythe following structural formula: ##STR1## in which Ac represents apharmaceutically acceptable acyl group known to be of utility as asubstitutent on the 7-amino group in the structures of known or priorart cephalosporins or on the 6-amino group in the structures of known orprior art penicillins with the provision that Ac does not contain asubstituted or unsubstituted thiazole (or thiazoline) moiety.

Representative acyl substituents are: ##STR2## wherein: X is thienyl,furyl, phenyl or phenyl monosubstituted with hydroxy, hydroxymethyl,formamido or ureido;

A is NH₂, OH, COOH, SO₃ H, formyloxy or, when the α-C-hydrogen isabsent, methoxyimino;

Y is cyano, sydnone, pyridone, thienyl, o-aminomethylphenyl, phenyl ortetrazolyl;

Z is methyl, trifluoromethyl, trifluoroethyl, pyridyl or cyanomethyl;and

M is zero to two.

Each of the three partial structures above represent subgeneric groupsof compounds covered by this invention.

Representative 7-acylamino substituents of the compounds of Formula Iare listed below:

α-hydroxyphenylacetamido

α-aminophenylacetamido

α-amino-4-hydroxyphenylacetamido

Trifluoromethylthioacetamido

2,2,2-trifluoroethylsulfinylacetamido

2,2,2-trifluoroethylthioacetamido

Cyanoacetamido

α-carboxythienylacetamido

α-carboxyphenylacetamido

α-sulfophenylacetamido

Methylsulfonylacetamido

Cyanomethylthioacetamido

3-sydnoneacetamido

1-tetrazolylacetamido

2-thienylacetamido

Syn-2-methoxyimino-2-α-furylacetamido

4-pyridylthioacetamido

O-aminomethylphenylacetamido

Others together with N-acylation procedures may be found inCephalosporins and Penicillins, Flynn, Academic Press, 1972; U.S. Pat.Nos. 2,721,196 and 3,953,424; Belgian Pat. No. 832,725; German Pat. Nos.2,127,285 and 2,406,165.

It will be recognized that the 4-carboxylic acid group of the compoundsof Formula I may be readily esterified by methods well known to the art.These esters include, for example, simple alkyl and aryl esters as wellas esters which are easily cleaved, within the body, to the parent acidsuch as indanyl, pivaloyloxymethyl, acetoxymethyl, propionyloxymethyl,glycyloxymethyl, phenylglycyloxymethyl and thienylglycyloxymethyl estersand others. Of course, when A is COOH, this group may be similarlyesterified. All such ester derivatives are included within the scope ofthis invention.

Also covered in this invention are the pharmaceutically acceptable,nontoxic derivatives of the compounds of Formula I from which theyderive utility: the salts, as stated above easily split ester or etherderivatives of either a carboxy or hydroxy function, amide derivativesat an amino radical such as in a 7-glycylamino group as thefuryl-,pyranyl-, oxolanyl- or oxiranyl-carbonyl amides (i.e. BelgianPat. No. 835,295), the solvates such as hydrates, glycolates oralcoholates. As examples of these, one skilled in the art would be ableto prepare and use the alkali metal salts such as the sodium orpotassium salts (for example using sodium or potassium 2-ethylhexanoate), ammonium salts, organic amine salts such as those withprocaine or dibenzylethylenediamine.

Other known cephalosporin modifications can be made by known syntheticprocedures such as introduction of an α-methoxy group at position 7,preferably at the stage of the 7-aminocephalosporanic acid reactantsdisclosed below (IV), prior to N-acylation. Optical isomers are alsopossible such as with the mandeloyl or phenyl glycyl substituents at 7.The D-forms of these subgeneric groups are preferred.

The compounds of this invention are most conveniently prepared by adisplacement of the acetoxy group of a known 7-acylaminocephalosporanicacid (II) by 3-sulfomethyl-1,2,4-triazole-5-thiol (III). Alternatively asimilar displacement with the thiol can be run on 7-aminocephalosporanicacid to give7-amino-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid (IV) which may then be N-acylated as known to the art as describedabove. Suitable protective groups may be used in either method as isknown to the art (see "Protective Groups in Organic Chemistry". J. F. W.McOmie, Plenum Press, 1973, Chapters 2 and 3 for use of amino, carboxy,sulfo or hydroxyl protective groups).

For example, the t-butyl (for COOH) or t-butoxycarbonyl (for NH₂) groupsare easily removed by treatment with trifluoroacetic acid.

The compounds of Formula I have antibacterial activity against eitherGram positive or Gram negative bacteria with minimum inhibitoryconcentrations (MIC's) in vitro from 0.4 to 200 μg/ml. Test results for7-D-(-)-mandelamido-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid, disodium salt, dihydrate (A) are:

    ______________________________________                                                      A      Cefazolin                                                                              Cephalothin                                     ______________________________________                                        S. aureus HH 127                                                                              3.1      0.4      0.2                                         S. aureus SK 23390                                                                            3.2 (1.6)                                                                              0.2      0.2 (0.1)                                   S. aureus villaluz SK 70390                                                                   >200     200 (100) 50                                         Strep. Faecalis HH 34358                                                                      200      6.3      12.5                                        E. coli SK 12140                                                                              0.8 (1.6)                                                                              0.8      6.3 (3.1)                                   E. coli HH 33779                                                                              1.6      1.6 (0.8)                                                                              6.3                                         Kleb. pneumo. SK 4200                                                                         0.8      1.6      1.6 (3.1)                                   Kleb. pneumo. SK 1200                                                                         0.4 (0.8)                                                                              0.4 (0.8)                                                                              1.6 (3.1)                                   SalmonellaATCC 12176                                                                          0.8      0.8      0.8 (1.6)                                   Pseudo. aeru. HH 63                                                                           >200     >200     >200                                        Serratia marc. ATCC 13880                                                                     25       >200     >200                                        Proteus morgani 179                                                                           25 (12.5)                                                                              200      >200                                        Entero. aerog. ATCC 13048                                                                     1.6      12.5                                                 Entero. cloacae HH 31254                                                                      1.6      0.8      6.3                                         Proteus mirbilis PN-444                                                                       0.8      3.1      3.1                                         ______________________________________                                    

Compound A gave an ED₅₀ in mice of 1.02 mg/kg (s.c.) and 26 mg/kg (p.o.)against E. coli, 1.02 mg/kg against Kleb. pneumo. (s.c.). Cephalexingives comparable values of 12.5 (s.c.) and 25 (p.o.) against E. coli.Cephaloridine gives a comparable value of 6.25 (s.c.) against Kleb.pneumo.

Pharmaceutical compositions having antibacterial activity which comprisea pharmaceutical carrier containing an active but nontoxic quantity of acompound of Formula I as well as methods of combatting bacterialinfections by administering such a composition to an infected animal orhuman host in a nontoxic amount sufficient to combat such infections arealso objects of this invention. The administration may be orally or byparenteral injection such as subcutaneously, intramuscularly orintravenously. The injection of suitably prepared sterile solutions orsuspensions containing an effective, nontoxic amount of the newcephalosporin compound is the preferred route of administration.

The compounds of Formula I are formulated and administered in the samemanner as other prior art cephalosporins such as cephazolin orcephalothin. The dosage regimen comprises administration, preferably byinjection, of an active but nontoxic quantity of a compound of Formula Iselected from the dosage unit range of from about 250 mg to 600 mg withthe total daily dosage regimen being from about 750 mg to 6 g. Thecompounds as their sodium or potassium salts are very water solublecompared with non-sulfo congeners in the art. The precise dosages aredependent upon the age and weight of the subject and on thesusceptibility of the infection being treated to each individual. Thesecan be determined by those skilled in the art based on the datadisclosed herein compared with that available to the art attained withthe known cephalosporins outlined herebefore.

The following examples illustrate the invention but are not to beconstrued as limiting the scope thereof. Temperatures are in degreesCentigrade (° C.) unless otherwise stated.

EXAMPLE 1

A mixture of 15.8 g (0.1 mol) of potassium sulfite in 10 ml of water and12.2 g (0.1 mol) ethyl chloroacetate in 50 ml of ethanol was warmed atgentle reflux for 4 hours then stirred at room temperature overnight.The solid was collected, washed with ethanol and air dried to givepotassium ethoxycarbonylmethane sulfonate (Beilstein 4, II, 532), m.p.213°-218°.

A mixture of 17.3 g (0.84 mol) of the methanesulfonate in 840 ml ofwater with 37.8 g (37.8 ml, 1.18 mol) of hydrazine was heated at refluxovernight. The solution was evaporated to a syrup which began tocrystallize partially. The syrup was dissolved in 300 ml warm water,filtered, and methanol was added to the filtrate. Scratching gavecrystals which were the desired potassiumhydrazinocarbonylmethanesulfonate.

The hydrazide (19.2 g, 0.1 mole) and 16.5 (0.1 mol) of thecarbamodithioic acid anhydrosulfide with ethyl carbonate were mixed with250 ml of 1:1 water-ethanol and heated at reflux overnight. The mixturewas taken to pH 10-11 with 10% aqueous sodium hydroxide and heated on asteam bath for 1 hour. After cooling overnight the solution wasevaporated to dryness. The residue was taken up in warmdimethylformamide. The insoluble material was collected. The filtratewas evaporated to a heavy oil which was treated with methanol to give asolid. A second crop was also obtained to give, with m.p. 318.5°-319.5°,the hydrated sodium salt of 5-mercapto-1,2,4-triazole-3-methane sulfonicacid or 3-sulfomethyl-1,2,4-triazole-5-thiol. Treatment of an aqueoussolution of the salt with a strongly acidic ion-exchange resin followedby lyophilization gives the acid. This acid and its alkali metal saltssuch as the sodium or potassium salts are important new intermediates.

A mixture of 6.4 g (0.015 mol) of 7-D-(-)-mandelamidocephalosporanicacid and 2.21 (0.01 mol) of 3-sulfomethyl-1,2,4-triazol-5-thiol sodiumsalt one quarter hydrate in 75 ml of water was taken to pH 6.8 withsolid sodium bicarbonate. The solution was stirred at 67° for 6 hours.The mixture was layered with ethyl acetate then acidified to pH 1.5 with6N sulfuric acid. The layers were separated. The aqueous layer wasreextracted with ethyl acetate. The aqueous phase was adjusted to pH 6.8for overnight storage then taken to pH 1.8 prior to passing over anXAD-7 resin column (a crosslinked polymer of acrylic esters with anaverage pore diameter of 80 A). Elution with water gave a series ofproduct-containing eluates which were combined and evaporated. The syrupleft after evaporation was taken up in 75 ml of water and lyophilized.

The lyophilizate was then taken up in 12.5 ml. of methanol. Afterfiltration, the filtrate was evaporated to half volume then treated withdiethyl ether to precipitate a solid which was dissolved in water andlyophilized to give a fluffy white solid,7-D-(-)-mandelamido-3-(3-sulfomethyl-1,2,4-triazol-5-thiomethyl)-3-cephem-4-carboxylicacid disodium salt dihydrate.

Anal. Calcd. C, 36.71; H, 3.40; N, 11.25. Found: C, 36.89; H, 3.83; N,11.32.

EXAMPLE 2

A mixture of 5.22 g (10.0 mmol) of7-(D-α-t-butoxycarbonylamino-4-hydroxyphenylacetamido)cephalosporanicacid and an excess (15.0 mmol) of 3-sulfomethyl-1,2,4-triazol-5-thiol in75 ml of pH 6.4 phosphate buffer solution is treated with sufficientsodium bicarbonate to give a pH of 6.4. The mixture is heated at 70° for3 hours, cooled, acidified with dilute hydrochloric acid to pH 2 andextracted with ethyl acetate. The aqueous solution is adjusted to pH 7.0with sodium bicarbonate and added to a XAD-7 resin column. Elution withwater and then methanol followed by evaporation of the productcontaining fractions gives the t-boc derivative of the desired compound.This derivative is stirred at 25° C with 25 ml of trifluoroacetic acidand 25 ml of 1,3-dimethoxybenzene for 2 hours. The mixture is evaporatedto dryness, ether added to the residue and the precipitated saltcollected. This is dissolved in water and one molecular equivalent ofsodium bicarbonate is added. The solution is lyophilized and thentritrated with acetone to give7-(D-α-amino-4-hydroxyphenylacetamido)-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid. Similar treatment of the t-boc derivatives of the7-DL-(α-aminophenylacetamidocephalosporanic acid gives the corresponding7-DL-(α-aminophenylacetamido)-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylic acid.

EXAMPLE 3

A mixture of an excess (12.2 mmol) of3-sulfomethyl-1,2,4-triazol-5-thiol, 32.5 mmol of sodium bicarbonate and8.1 mmol of 7-trifluoromethylthioacetamidocephalosporanic acid in 50 mlof water is stirred at 70° for 5 hours. The reaction mixture is cooledand passed over XAD-2 resin with water and methanol as eluants. Themethanol eluants are evaporated to dryness to give a residue which isdissolved in a small amount of water and lyophilized to give7-trifluoromethylthioacetamido-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid disodium salt. Substituting 7-(2-thienylacetamidocephalosporanicacid gives7-(2-thienylacetamido)-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid disodium salt.

Stoichiometric quantities of cephalosporanic acids having the individual7 -acylamino substituent listed hereabove may be substituted in Examples1-3 with variations which will be obvious to those skilled in this art.

EXAMPLE 4

An injectable pharmaceutical composition is formed by adding sterilesaline solution (2ml) to 500 mg of the product of Example 1. Thismaterial is injected parenterally four times daily to a human patientinfected with susceptible bacteria. Other compounds of this inventionmay be similarly used.

What is claimed is:
 1. A compound of the formula: ##STR3## in which: Xis thienyl, furyl, phenyl or phenyl monosubstituted with hydroxy,hydroxymethyl, formamido or ureido; andA is NH₂, OH, COOH, SO₃ H,formyloxy or, when the α-C-hydrogen is absent, methoxyimino; or itsnontoxic pharmaceutically acceptabe alkali metal salts.
 2. The compoundof claim 1 being7-D-mandelamido-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid.
 3. The compound of claim 1 being7-D-mandelamido-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid disodium salt.
 4. The compound of claim 1 being7-(D-α-amino-4-hydroxyphenylacetamido)-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid.
 5. The compound of claim 1 being7-DL-(α-aminophenylacetamido)-3-(3-sulfomethyl-1,2,4-triazol-5-ylthiomethyl)-3-cephem-4-carboxylicacid.
 6. A pharmaceutical composition having antibacterial activitycomprising a quantity of a compound which is antibacterially effectivebut nontoxic and is claimed in claim 1 and a pharmaceutically acceptablecarrier therefor.
 7. A method of treating bacterial infectionscomprising administering internally to an infected or susceptible humansubject an antibacterially effective but nontoxic dose of a compound asclaimed in claim 1.